Using XML for a publicatin framework

Hi All, 
We are in the process of designing a Java Publication framework, and we are
evaluating how Java & XML can support our needs.

This is how we are looking to architect the website:
- Map the website into multiple pages
- Each page has a XML file associated with it, and its corresponding XSL
file. 
- A XML file can be composed of both text (for content) and other "complex"
tags( I would refer to this as a gadget, which embeds a functinonality in
itself).
- A gadget inturn has a XML and XSL associate with it, and can have both
static data and other gadgets.
(Thus a page is composed of a recursive set of gadgets or tags which have
their own XML/XSL)

An example of a page:

Lets assume that a Web page(MainPage) has a left sidebar, top bar, main
navigation and right side bar.The right sidebar inturn has a search box,
related links section, and personalized data.

The XML for "MainPage" as follows:
<Root>
<Gadget name="rightsidebar" handler="..">
<Gadget name="topbar" handler="..">
<Gadget name="leftsidebar" handler="..">
<Gadget name="maincontent" handler="..">
</Root>

The XML for "leftsidebar" as follows:
<Gadget name="search" handler="..">
<Gadget name="relatedlinks" handler="..">
<Gadget name="MyOptions" handler="..">


The XML for "search" as follows:
<Root>
<Search Option="section1">
</Root>

.....

So what we want to do here is have the xsp call the main XML page, which
will call the xsp for the gadget, and this will happen in a recursive manner
till all gadgets are resolved, and the final page is displayed with content.

Questions: 
- Are there XML Parsers/frameworks that supports such recursive resolution
of gadgets, or can something like this be practical to build and maintain.
- Has anyone used cocoon and used it to fulfill such a framework.

Any help is highly appreciated.
- Yogi.